We are interested in the cellular response to viral infection and how that correlates to host pathogenesis. As our model, we study mengo virus infection of murine macrophages. Mengo virus infection is useful to study in that the pathogenesis of mengo virus infection in mice is well characterized. During mengo virus infection, a cellular sentinel protein, protein kinase R (PKR), is relocalized from a uniform cytoplasmic distribution to a perinuclear locale. PKR has been implicated as being important in the cellular response to many other virus infections including, HIV-1, adenovirus, and vaccinia virus. So, PKR may have a universal role in the cellular response to viral infections. To understand how mengo virus infection elicits a relocalization of PKR in infected cells and how this is important in the cellular response to viral infection, we have created a panel of attenuated mengo viruses. We wish to use indirect immunofluorescence and confocal microscopy to determine if these viruses are impaired in the ability to elicit a relocalization of PKR in infected cells.